Experimental Investigation on Triggered Vacuum Arc and Erosion Behavior Under Different Contact Materials

In order to improve the breaking capacity of contacts, it is very important to find a better contact material. In this paper, the triggering experiments of plate contact with different materials are studied to investigate the characteristics of vacuum arc. The current range is from 1 to 9 kA (rms). The gap distance is selected as 3 and 5 mm. The arc appearance and the behavior of cathode spots are captured by high-speed camera with an exposure time of 2 μs. The surface topography of contacts after experiments is evaluated by scanning electron microscope. The arc current and arc voltage are measured at the same time by Rogowski coil and high-voltage probe. The diameter of the contact is 25 mm. There are seven kinds of materials (CuCr
₁₀
, CuCr
₂₅
, CuCr
₃₀
, CuCr
₄₀
, WCu
₁₀
, WCu
₃₀
, and CuW-WC) conducted in this paper. Compared with the experimental results, the arc of WCu alloy distributes more evenly on the contact plane with many bright cathode spots. The small gap distance makes the burning point more fixed. The arc of CuW-WC is unstable. During the arc trigger moment to the arc stable burning stage, the radial diffusion velocity of WCu
₁₀
cathode spot is the lowest with about 25% of CuCr
₁₀
. CuCr
₁₀
alloy has the worst melting resistance. WCu alloy has good melting resistance and bad toughness. The toughness of CuW-WC is even worse. Under the low current, CuCr
₃₀
might be preferred for vacuum interrupters from the cathode spots' radial diffusion speed, arc appearance, and erosion result. When the current increasing, the arc can easily spread to the entire surface of WCu contact, and WCu
₁₀
would be the prefer material with the diffusion arc and good erosion resistance.